Applied Mechanics and Materials Vols. 204-208

Abstract: Ports at high siltation rates are covered with fluid mud layers which generally develop from short-term siltation. The presence of a fluid mud layer on the bottom of the channel has a considerable influence on ship behaviour, e.g. squat. The paper calculates siltation in an approach channel and its effect on ship motions. Firstly, siltation thickness and sediment density are predicted based on existing information of sediment, and the characteristics of mud layers are analyzed, Secondly, the squat and trim of ship navigating in the muddy areas are computerized. Finally a model through Monte Carlo simulation is presented to interpret the probability of ship grounding on the fluid mud layer.

Abstract: The solution of linearly elastic and orthotropic solid bodies is very complicated, thus a new element model for solving linearly elastic and orthotropic bodies is presented by using the generalized Hooke's law and the superposition principle. This new model is a simple truss consisting of some bars, and then the solution of orthotropic body becomes simple. Furthermore, this new model reveals the physical mechanism of a solid body under the action of applied forces.

Abstract: The efficiency of the element removal or addition is of significance for evolutionary structural optimization (ESO) process. The key is to find an appropriate rejection criterion (RC) which allows to assess the contribution of each element to the specified behavior（stress, stiffness, displacement, etc.）of the structure, and to subsequently remove elements with least contribution. This paper proposed a varying elements removal ratio (VERR) method which uses a larger ERR (Element Rejection Ratio) value at early iterations where exist a lot of redundant material, and decreases the value of ERR in the optimal process to lessen the number of elements removed at later iterations. Meanwhile, this paper proposed a strategy for element addition based on stress level and the contribution of elements to the structure in order to decide which elements should be added to the model and the sequence of the element addition. With the proposed VERR and the strategy, the optimization procedure of the structure evolves more quickly and smoothly.

Abstract: In this paper we consider the Cauchy problem of the Davey-Stewartson system on a circle. We establish, from a mathematical aspect, certain apriori estimates necessary to ensure the existence and uniqueness of solutions of the Davey-Stewartson system model.

Abstract: According to the interaction between lamellar inclusion and interphase, forth-phase model is suggested to determine the micro-stress-field distribution of three-phase cell in eutectic composite ceramic. On the basis of the volumetric average strain, the effective compliance tensor increment of eutectic composite ceramic is obtained. The remote stress boundary condition of the eutectic composite ceramic is accounted for getting the micro-stress-field of lamellar inclusion in eutectic composite ceramic. Analysis shows that the micro-stress-field of the lamellar inclusion in eutectic composite ceramic is associated with the stiffness and the volume fractions of each component in eutectic composite ceramic, the shape of interphase and lamellar inclusion. The-micro-stress field has apparent size effect: three direction stresses increase with the thickness of lamellar inclusion.

Abstract: Based on the further analysis to triple-shear unified yield criterion, the Lode parameter expression of the triple-shear unified yield criterion were given. This paper performs the analysis computation to softening material thick-walled cylinder under internal pressure based on triple-shear unified yield criterion. The analytical solution of stress and displacement is obtained. By using triple-shear unified yield criterion, more reasonable solution for different softening material can be derived.

Abstract: It is necessary for us to monitor and forecast deformation as harm of deformation is tremendous. At the same time, deformation is seen as power system with chaos features because process of deformation is easily influenced by geology、hydrology、earthquake and activity and so on. On the base of chaos theory, forecasting model based on the maximal Lyapunov exponent is put forward in this paper, and is checked by example of engineering. Research indicate that Chaos phenomenon exist in deformation sequence for Lyapunov exponents is bigger than 0. The forecasting results show that forecasting method based on maximal Lyapunov exponent has high predictive precision, so the method is proved to be feasible and referenced.

Abstract: The existing research on flange focused on bearing capacity, and there were few reports on the rigidity of flange. In this paper, rigidity test was carried on for the connection of rigid flange and flexible flange in power-transformed frames. According to the test results, the axial rigidity, shear rigidity and flexural rigidity was compared. The results indicated that the axial rigidity, shear rigidity and flexural rigidity of flexible flange connection was lower than those of rigid flange connection for both the plain bolt and high strength bolt.

Abstract: The explicit dynamic finite element theory is applied on the collision of ships with buoys for computer simulation. Using ANSYS/LS-DYNA finite element analysis software, the numerical simulation of the collision between the ton ship and the buoy with different structures and impact points. The collision force, deformation, displacement parameters and the weak impact points of a buoy are obtained. Based on the numerical simulation results, analysis of buoys and structural collision damages in anti-collision features are discussed, and several theoretical sugestions in anti-collision for the design of buoy are provided.

Abstract: Differential Transform Method (DTM) is a new semi-analytical, semi-numerical algorithm, which transforms differential equations to the form of Taylor series. The method derives an approximate numerical solution based on Taylor series expansion, which is a analytical solution built on polynomial form. Traditional Taylor series method is used for symbolic computation, while the differential transform method obtained the solution of the polynomials through itineration calculations. Applying DTM to buckling problems, the critical length of a bar with pinned-clamped boundary condition is studied. The computational results are compared with analytical solutions and shown excellent agreement between those two algorithms. The method adds a new tool for computational engineering mechanics.